In Patent Literature 1, a pair of imaging elements take an image of light entered through a pair of objective lenses of digital binoculars to acquire a pair of images (stereo images) with a difference equivalent to a binocular parallax, a geometric difference in image structure equivalent to the binocular parallax is recognized for the pair of images stored in a memory after various corrections, and a noise reduction process of reducing a difference (for example, difference in random noise superimposed on the pair of images by the imaging elements) other than the recognized geometric difference in image structure is executed. An image after the noise reduction process is displayed on a display device. The user views (stereoscopic vision) the image displayed on the display device through an eyepiece.
Patent Literature 2 discloses a three-dimensional image pickup apparatus including: imaging units that take images of a subject and that generate two image data of a left-eye imaging area and a right-eye imaging area by a stereo adapter; a camera shake correction unit that calculates an amount of position correction based on camera shake; a zoom control unit that controls zooming of the imaging units; a size determination unit; a position determination unit; a cut-out unit that cuts out left and right image areas for generating appropriate stereoscopic vision; an enlargement/reduction unit; and a combining unit and a recording unit that combine the left and right image areas for generating the stereoscopic vision from the left and right eyes.
As described in Patent Literature 3, systems of camera shake correction in an imaging apparatus include an electronic system, an optical system, and a sensor (imaging element) shift system.
As described in Patent Literature 4, two or more cameras arranged at different positions are used to image a subject, corresponding points as corresponding pixels between a plurality of images (a base image taken by a base camera and a reference image taken by a reference camera) acquired by the imaging are searched (stereo matching), differences in positions (parallax) between the corresponding pixels on the base image and pixels on the reference image are calculated, a principle of triangulation is applied to the parallax to measure distances from the base camera or the reference camera to the points on the subject corresponding to the pixels, and a distance image indicating a stereoscopic shape of the subject can be generated. In the stereo matching, there are a plurality of points on a real space mapped to the pixels on the base image, and therefore, based on the fact that pixels' on the reference image corresponding to the pixels exist on a straight line (epipolar line) as a map of the points on the real space, corresponding points as the pixels on the reference image corresponding to the pixels are searched. In the stereo matching, a correlation window including the pixels as targets of the corresponding point search is set on the base image, the same correlation window as the correlation window set to the base image is moved along the epipolar line on the reference image, a correlation of each pixel in the correlation window on each image is calculated for each movement position, and pixels at the central position of the correlation window in which the correlation on the reference image is greater than a predetermined threshold are obtained as the corresponding points of the pixels.
As described in Patent Literature 5, examples of methods of searching corresponding points between different viewpoint images include Sum of Absolute Difference (SAD method) and Phase-Only Correlation (POC method).
As described in Patent Literature 6, measurement target images in the pair of images always exist on corresponding straight lines in the pair of images even if the distance and the position are different as long as there is no optical distortion or the like. The straight lines are called epipolar lines, and the optical distortion or the like is corrected in advance to form straight lines. Correlations on the straight lines are calculated in the calculation of the correlations, and the positional relationship between the images obtained by the left and right cameras is calculated. If the camera is formed so that the epipolar lines are at horizontally equal positions in both images, the amount of calculation in the image processing is reduced, and the process improves.